change cryptomatte setitings with python
View the UI source

In User Preferences &gt; Interface &gt; Display turn on developer extras. Sounds like you already have.  When the path in button hover is dodgy, if available click view source on a field of interest.

In this case it opens addons/cycles/ui.py in text editor at or around the CryptoMatte draw panel where this leaps out

cycles_view_layer = context.view_layer.cycles


Off to the python console:

&gt;&gt;&gt; cycles_view_layer
bpy.data.scenes['Scene']...CyclesRenderLayerSettings

&gt;&gt;&gt; cycles_view_layer.use_pass_crypto_
                                      asset
                                      material
                                      object
&gt;&gt;&gt; cycles_view_layer.use_pass_crypto_object
True

&gt;&gt;&gt; cycles_view_layer.pass_crypto_
                                  accurate
                                  depth
&gt;&gt;&gt; cycles_view_layer.pass_crypto_depth
6

&gt;&gt;&gt; cycles_view_layer.pass_crypto_depth = 10
&gt;&gt;&gt; 


can put in accurate mode with

cycles_view_layer.pass_crypto_accurate = True


Some more fiddling, the property is displayed as belonging to scene

&gt;&gt;&gt; cycles_view_layer.id_data
bpy.data.scenes['Scene']

&gt;&gt;&gt; C.scene.view_layers['RenderLayer'].cycles
bpy.data.scenes['Scene']...CyclesRenderLayerSettings

&gt;&gt;&gt; cycles_view_layer
bpy.data.scenes['Scene']...CyclesRenderLayerSettings

&gt;&gt;&gt; C.scene.view_layers['RenderLayer'].cycles is cycles_view_layer
False

&gt;&gt;&gt; C.scene.view_layers['RenderLayer'].cycles == cycles_view_layer
True